The subject matter disclosed herein relates to a rotor ice protection system and, more particularly, to a rotor ice protection system that is designed to a first level of assurance but can be stepped up to a second level of assurance.
In aircraft design, a design assurance level (DAL) or an “Item Development Assurance Level” (IDAL), as defined by DO-178B, is determined from a safety assessment process and hazard analysis by examining the effects of a failure condition in the system. The failure conditions are categorized by their effects on the aircraft, crew and passengers and include catastrophic failures and hazardous failures. DAL A signifies catastrophic failures that may cause a crash and involve errors or loss of critical functions that are required to safely fly and land an aircraft. DAL B signifies hazardous failures that have a large negative impact on safety or performance, or reduce the ability of the crew to operate the aircraft due to physical distress or a higher workload, or cause serious or fatal injuries among the passengers.
For particular components, then, a component that is designed to be DAL A certified is designed with the understanding that a failure of the component will have a catastrophic effect on the aircraft. Thus, a DAL A certified component has to have a certain level of redundancy or failure mitigation capabilities to reduce the likelihood that a catastrophic failure will occur. By contrast, a component that is designed to be DAL B certified is designed with the understanding that a failure of the component will only have hazardous effect. Moreover, conventional modifications of a DAL B certified component in order to make the component DAL A certifiable require complete redesigns or the imposition of significant additional mechanical or electrical components.